1. Field of the Invention
This invention relates in general to valve assemblies and in particular to control valves for water.
2. Description of the Prior Art
There are various valve designs which attempt to provide for the control of fluid from an inlet point to an outlet point in good-sealing, long-wearing, reliable and low-cost manner. Unfortunately, features best achieving certain of these advantages are not always compatible with one another. Often, one desirable feature must be compromised in order to use a different advantageous feature. Some examples of efforts to achieve some of the above advantages are disclosed by the following patents:
______________________________________ Patent No. Patentee Issue Date ______________________________________ 2,704,650 Rand 3/22/55 2,893,687 Huthsing 7/07/59 2,952,439 Koons 9/13/60 3,199,833 Skinner 8/10/65 ______________________________________
These prior art efforts did not result in the creation of a device possessing all the above-mentioned advantages. The device of Manville, U.S. Pat. No. 3,552,714, issued on Jan. 5, 1971 and assigned to the assignee of the present application, was the result of a successful effort to achieve the aforementioned advantages.
Although these prior art devices focus primarily on the design of a valve seal and valve seat, the typical valve construction in which such seals and seats are used further include a valve body and a stem threadedly received by the body. The valve seal member is normally attached to the end of the stem in such a manner that as the stem is advanced into the valve body the seal is advanced into sealing engagement with the valve seat. Some such valves, as shown by the Manville patent, include a valve seat member which has a hexagonally-shaped recess aperture in order to permit removal of the valve seat member by use of an allen wrench when the knob and stem portions of the valve assembly are removed. The Manville device also includes the feature of retaining the valve seal on the end of the stem by using a retaining ring which is received in a groove on the valve stem and fits snugly in the valve seal member.
Inherent with any valve device is the fact that as more machining is required to be performed on the component pieces, such as internal and external threads and retaining ring grooves, the associated cost of the valve assembly increases. In addition, these prior art devices which rely on the hexagonally-shaped aperture as the means by which the valve seat can be removed, have the disadvantage that if the valve seat is tightly threaded in place, sufficient loosening torque may not be able to be developed through the allen wrench before the hexagonal aperture is stripped (rounded). In the event the aperture is stripped, the removal of the seat may be virtually impossible without the complete disassembly of the entire valve assembly.